Temperature Converter
Temperature conversions for Kelvin, Celsius, Fahrenheit, Rankine, Delisle, Newton, Réaumur, and Rømer.
Celsius, Fahrenheit and Kelvin
Celsius is the most widely used temperature scale worldwide. Fahrenheit is mainly used in the United States. Kelvin is the SI unit of temperature and starts at absolute zero (0 K = −273.15 °C). The formula to convert Celsius to Fahrenheit is: °F = °C × 9/5 + 32.
Historical Temperature Scales
Beyond the well-known scales, there are historical alternatives: Rankine is the absolute Fahrenheit scale. Delisle was used in 18th-century Russia. Newton, Réaumur, and Rømer were early scientific scales before Celsius and Kelvin became standard.
Absolute Zero
Absolute zero is the lowest possible temperature: 0 K, −273.15 °C, −459.67 °F, or 0 °R (Rankine). No further heat can be removed below this point. It forms the basis for both the Kelvin and Rankine scales.
Frequently Asked Questions
Answers to common questions about temperature conversion
The formula is: °F = °C × 9/5 + 32. Example: 100 °C = 100 × 1.8 + 32 = 212 °F. Conversely: °C = (°F − 32) × 5/9. Key reference points: 0 °C = 32 °F (freezing), 100 °C = 212 °F (boiling), 37 °C = 98.6 °F (body temperature).
Absolute zero is the lowest possible temperature, at which the thermal motion of particles is minimized. It is 0 K, −273.15 °C, or −459.67 °F. No energy can be extracted below this temperature. The Kelvin scale starts exactly at this point.
Rankine is the absolute Fahrenheit scale — similar to how Kelvin is the absolute Celsius scale. The zero point is absolute zero (0 °R = 0 K), but the degree size corresponds to Fahrenheit. 0 °R = −459.67 °F = −273.15 °C. The scale is mainly used in American engineering.
The Delisle scale was developed by Joseph-Nicolas Delisle in 1732. It is inverted compared to Celsius: higher temperature corresponds to a lower Delisle value. The boiling point of water is 0 °De, the freezing point is 150 °De. Formula: °De = (100 − °C) × 3/2.
Historically, various scientists developed their own scales for their research. Daniel Fahrenheit, Anders Celsius, William Thomson (Kelvin), Isaac Newton, and others defined scales based on different reference points. Today, Celsius (everyday use) and Kelvin (scientific) are most common, while Fahrenheit dominates in the United States.